Factors affecting cellulose and hemicellulose hydrolysis of alkali treated brewers spent grain by Fusarium oxysporum enzyme extract
ABSTRACT The enzymatic degradation of polysaccharides to monosaccharides is an essential step in bioconversion processes of lignocellulosic materials. Alkali treated brewers spent grain was used as a model substrate for the study of cellulose and hemicellulose hydrolysis by Fusarium oxysporum enzyme extract. The results obtained showed that cellulose and hemicellulose conversions are not affected by the same factors, implementing different strategies for a successful bioconversion. Satisfactory cellulose conversion could be achieved by increasing the enzyme dosage in order to overcome the end-product inhibition, while the complexity of hemicellulose structure imposes the presence of specific enzyme activities in the enzyme mixture used. All the factors investigated were combined in a mathematical model describing and predicting alkali treated brewers spent grain conversion by F. oxysporum enzyme extract.
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ABSTRACT: a b s t r a c t Consolidated BioProcessing (CBP) can provide an important contribution to reducing ethanol production costs and moving from cellulosic feedstock to fuel ethanol tanks. Several efforts have so far been focused mainly on CBP category II engineering an ethanologen yeast or bacterium to be cellulolytic, but the limited ability of the category II CBP system for producing enzymes for lignocellulose degradation remains a challenge. As an alternative, category I CBP, aimed at engineering a cellulase producer to be ethanologenic, could be pursued, but it is still in its infancy. Some cellulolytic thermophilic bacteria have been described as potential candidates for category I CBP. However, only fungi naturally produce the needed titers of cellulases required for the complete saccharification of pretreated lignocellulose. In this review, potential of cellulolytic fungi as candidates for category I CBP is discussed.Renewable and Sustainable Energy Reviews 02/2012; 16(5):3286-3301. DOI:10.1016/j.rser.2012.02.050 · 5.51 Impact Factor
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ABSTRACT: Purpose Brewers spent grain (BSG) is a by-product of the brewing process corresponding to around 85% of total by-products generated. The great number of publications over the last 5 years, on the biotechnological applications of BSG, represents the increased scientific interest on it. This critical, state of the art review aims at gathering and analysing the most recent scientific efforts on the bio-technological potential of Brewer's spent grain and on its evaluation as a feedstock for high added value products. Methods The assiduous bibliographic retrospection focused on the latest scientific reports. The consideration of all relevant scientific articles was thorough and critical. The classification of the scientific efforts was made not only according to the end-products but also according to the biotechnological approach adopted. Results BSG has been used in a wide range of biotech-nological applications such as substrate for enzymes pro-duction, as a source for value-added products (antioxidants, monosaccharides, oligosaccharides, xylitol, arabitol, bio-ethanol, biogas or lactic acid) or for the production of functional proteins and lipids. Its applications as a carrier in various bioprocesses have also been reported. Conclusion The implementation of BSG's fractionation in industrial scale seems to be the next step in BSG's exploitation. A fractionation process which allows the exploitation of biomolecules belonging to different classes, produced from one feedstock (BSG) may be used as a pattern for the implementation of the biorefinery concept in industrial scale, as long as the methods adopted ensure the functionality of the potentially valuable components.Waste and Biomass Valorization 06/2012; 3:213-232. DOI:10.1007/s12649-012-9108-8
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ABSTRACT: Cellulose rich barley straw, which has a glucan content of 62.5%, followed by dilute acid pretreatment, was converted to bioethanol by simultaneous saccharification and fermentation (SSF). The optimum fractionation conditions for barley straw were an acid concentration of 1% (w/v), a reaction temperature of 158 °C and a reaction time of 15 min. The maximum saccharification of glucan in the fractionated barley straw was 70.8% in 72 h at 60 FPU/gglucan, while the maximum digestibility of the untreated straw was only 18.9%. With 6% content WIS (water insoluble solid) for the fractionated barley straw, 70.5 and 83.2% of the saccharification yield were in SHF and SSF (representing with glucose equivalent), respectively, and a final ethanol concentration of 18.46 g/L was obtained under the optimized SSF conditions: 34 °C with 15 FPU/g-glucan enzyme loading and 1 g dry yeast cells/L. The results demonstrate that the SSF process is more effective than SHF for bioethanol production by around 18%.Korean Journal of Chemical Engineering 10/2012; 29(10). DOI:10.1007/s11814-012-0019-y · 1.24 Impact Factor